Limatium, Strong, Ellen E. & Bouchet, Philippe, 2018

Strong, Ellen E. & Bouchet, Philippe, 2018, A rare and unusual new bittiine genus with two new species from the South Pacific (Cerithiidae, Gastropoda), ZooKeys 758, pp. 1-18 : 3-4

Limatium gen. n.

Type species.

Limatium pagodula sp. n.

Diagnosis.

Shells of small size, 6 to 7 mm in adult length on average, with smooth, polished surface, golden honey to dark brown in color. Rachidian with hexagonal to septagonal basal plate, squarish to rectangular, with elevated central portion with rounded, U-shaped lower margin; cutting edge with three, sharply pointed cusps. Operculum paucispiral with large, subcentral nucleus.

Etymology

From the Latin adjective limatus, -a, -um, meaning polished, and the ending -ium of many cerithiid genera. Gender neuter.

Ecology.

All known specimens of Limatium come from the outer slope of barrier reefs or, in islands without a coral reef lagoon, from the slope of the fringing reefs in the South Pacific (Fig. 1). Not a single specimen has been collected within a coral reef lagoon. The few live-taken specimens come from a confirmed bathymetric range of 10-100 m, with empty shells, potentially carried downslope, occasionally dredged from deeper water.

Remarks.

Limatium differs from all other bittiine genera in the smooth, shiny, polished surface of the shell and its rich, golden honey to dark brown color. The two species known thus far are further distinguished by the distinctive white fascioles extending suture to suture and which may be a diagnostic feature of the genus, but further comparative material is required. No other bittiine is known to possess a rachidian basal plate that is hexagonal to septagonal in shape, with an elevated central portion; the cutting edge uniquely bears only three, sharply pointed, dagger-like cusps. The paucispiral operculum is also unique among bittiines as understood thus far.